1. Field of the Invention
This invention relates to machines and systems for automatically loading a test sample card having one or more reagent filled sample wells with fluid samples (e.g., samples containing microbiological agents), and for conducting optical analysis of the samples after reaction with the reagents. The invention is particularly suitable for use in biological, blood or chemical analysis machines, as well as immunochemistry and nucleic acid probe assay machines.
2. Description of Related Art
Biological samples can be reacted and subjected to chemical or optical analysis using various techniques, including transmittance and/or fluorescence optical analysis. The purpose of the analysis may be to identify an unknown biological agent or target in the sample, to determine the concentration of a substance in the sample, or determine whether the biological agent is susceptible to certain antibiotics, as well as the concentration of antibiotics that would be effective in treating an infection caused by the agent.
A technique has been developed for conducting optical analysis of biological samples that involves the use of a sealed test sample card containing a plurality of small sample wells. Typically, during manufacture of the cards, e.g. for microbiological analysis, the wells are filled with either various types of growth media for various biological agents, or else various concentrations of different antibiotics. The cards have an internal fluid passageway structure for allowing fluid to enter the wells of the card through a transfer tube port. An L-shaped integral transfer tube extends outwardly from the transfer tube port. The prior art method involved the manual insertion of one end of the transfer tube into the card and the other end into a test tube, and then the manual placement of the card with attached transfer tube and test tube into a vacuum filling sealing machine, such as the Vitek.RTM. Filler Sealer. The filling and sealing machine generates a vacuum, causing the fluid in the test tube to be drawn into the wells of the sample card.
After the wells of the card are loaded with the sample, the cards are manually inserted into a slot in a sealer module in the machine, where the transfer tube is cut and melted, sealing the interior of the card. The cards are then manually removed from the filler/sealer module and loaded into a reading and incubating machine, such as the VITEK.RTM. Reader. The reading and incubating machine incubates the cards at a desired temperature. An optical reader is provided for conducting transmittance testing of the wells of the card. Basically, the cards are stacked in columns in the reading machine, and an optical system moves up and down the column of cards, pulling the cards into the transmittance optics one at a time, reading the cards, and placing the cards back in the column of cards. The VITEK.RTM. reading machine is described generally in the Charles et al. patent, U.S. Pat. No. 4,188,280.
This arrangement has limitations, in that two machines, a filler/sealer and a reader, are required to process and analyze the cards. Furthermore, additional time and labor are required to conduct the complete analysis of the card.
Combining the several functions of biological sample processing and optical reading into a single automatic sample processing and reading machine poses substantial challenges. One particularly difficult challenge is to provide a way of conducting the vacuum loading of the cards, and to provide a way for moving the loaded sample card to incubation and optical reading stations. Another challenge is to design a transport system for moving the sample cards and receptacles about the machine to the various stations.
The present inventive automated sample testing machine achieves these goals by providing a machine that performs dilutions for susceptibility testing, fills the cards with the samples at a vacuum station, and seals the card by cutting the transfer tube, and conducts incubation and optical transmittance and fluorescence analysis of the cards, all automatically. The machine is capable of conducting simultaneous susceptibility and identification testing of a sample placed in a single test tube. The machine provides for rapid, automatic identification and susceptibility testing of the sample. In a preferred form of the invention, a number of different test samples are tested simultaneously, and moved in a sample tray or "boat" around the machine among the various stations. The tray receives a cassette that contains a plurality of test tubes and associated test sample cards. The machine provides for novel pipetting and diluting stations, permitting fluids to be added to the test tubes or transferred from one test tube to another.
The machine further has a unique test sample positioning system that moves the tray (with test tubes and cards) about the machine over a base pan. The design of the positioning system is such that it permits essentially a custom configuration of stations above the base pan. Expansion of the machine to include additional carousels and reading stations, or addition types in intermediate procession stations such as dilution stations or vacuum stations, can be readily accomplished.
These and still other features of the invention will be come more apparent from the following detailed description of a presently preferred embodiment of the invention.